The Animal Model Core will establish and maintain a facility which allows breeding and housing of mice to be used by all projects. This includes transgenic and mutated mice, some of which will need special care due to reduced vitality. The core will provide time-mated mice, embryos, blastocysts, and pseudopregnant foster mothers. The Animal Models core will coordinate its efforts with the Embryology Core, which will then provide the histological specimens requested by the individual investigators. In addition to this facility, the core will include a research project which will develop a mouse arterial injury model for studying smooth muscle and endothelial cell biology. Smooth muscle cell proliferation kinetics at various times after vascular injury and endothelial regrowth will be studied. At later stages, the role of growth factors in intimal lesion formation will be studied. When the injury model is established, it will be utilized by the collaborating investigators to study the behavior of mutant mice strains in this model. These mutants include mice which are: osteopontin-deficient, megakaryocyte-defective, NGF receptor-deficient, PDGF-alpha receptor- deficient chimera. The pup-intimal smooth muscle cell phenotype will also be studied in this model. Thus, the Animal Models core will provide vital support for all of the project discussed here, and will address important questions regarding growth regulation of vascular cells after injury in a specific manner.